<?php
     $id=$_POST['id'];
     $date=$_POST['date'];
     $num=$_POST['num'];
     $cd=$_POST['id'].$_POST['date'];
     require('sql.php');
    $sql = "update pinglun set zan='$num' where cd='$cd'";
    if($id!="")
    {
    mysqli_query($conn, $sql);
    }
    mysqli_close($conn);
?>